The present invention is a composition for use in the cooling systems of internal combustion engines. More particularly, the composition is an ethylene glycol-based antifreeze composition which is designed to protect aluminum water pumps, aluminum engine heads, and aluminum radiators from corrosion.
Generally, water is the accepted heat exchange medium for the cooling systems of internal combustion engines. Ethylene glycol is widely used to lower the freezing point of water and to raise its boiling point to enable the coolant to be used over a wider range of temperatures. Ethylene glycol and other such antifreezes tend to corrode the metals from which the internal combustion engines are made under the conditions of elevated temperature and aeration. Therefore, it has been necessary to add corrosion inhibitor compositions to the antifreeze solutions to lessen the corrosive effect of the solutions.
In recent years, automobile manufacturers have been using more and more aluminum as a lightweight material in the construction of internal combustion engines. Since aluminum reacts differently than other metals when exposed to the corrosive action of ethylene glycol antifreeze solutions, it has become necessary to develop corrosion inhibitor compositions which prevent or lessen corrosion of aluminum as well as of the other metals which are used in the construction of internal combustion engines. Prior to the development of the present invention, the antifreeze industry has been relatively unsuccessful in developing a practical effective corrosion inhibitor composition which prevents corrosion of aluminum as well as other metals.
The primary object of this invention, therefore, is to provide a novel combination of corrosion inhibitors suitable for use in the cooling system of an internal combustion engine in which a large amount of aluminum is exposed to the corrosive action of ethylene glycol antifreeze compositions.